密度估计 -Basic idea: Probability that a vector x will fall in region R is: P=p(x')dx (1) Therefore,the ratio k/n is a good estimate for the probability P and hence for the density function p. p(x)dx'=p(x)v (4) p(x)is continuous and that the region is so small that p does not vary significantly within it,we can write: k/n Pn(x)≡ where x is a point within and V the volume enclosed by E. equation(1)and (4)yields histogram:Therefore, the ratio k/n is a good estimate for the probability P and hence for the density function p. p(x) is continuous and that the region R is so small that p does not vary significantly within it, we can write: where x is a point within R and V the volume enclosed by R. equation (1) and (4) yields histogram: – Basic idea: Probability that a vector x will fall in region R is: 密度估计 ( ') ' ( ) (4)   p x d x  p x V   P = p(x')d x' (1) V k n p x n / ˆ ( ) 